Decades of research on pig enrichment has identified what works, what does not, and how to implement enrichment effectively in commercial pig production systems.
Pig enrichment science has matured considerably over the past three decades, moving from simple provision of any object to nuanced understanding of what satisfies which behavioral motivations. The key finding: pigs have strong drives to root, chew, and manipulate substrates — and only materials that satisfy these drives prevent the redirected behaviors (tail biting, ear biting, flank nosing) that emerge in barren environments. Chains and rubber objects score poorly in enrichment effectiveness research because they do not fulfill rooting and chewing drives. Straw, hay, compost, and wood materials score highly because they allow actual investigation and destruction. Complexity and novelty extend engagement: rotating three or four enrichment types on a schedule maintains motivational engagement better than providing one type continuously. Substrate depth matters — thin straw on slatted floors is largely ineffective; deep loose straw is highly effective. The best enrichment programs are built on this evidence base.